Papers
Topics
Authors
Recent
Gemini 2.5 Flash
Gemini 2.5 Flash
173 tokens/sec
GPT-4o
7 tokens/sec
Gemini 2.5 Pro Pro
46 tokens/sec
o3 Pro
4 tokens/sec
GPT-4.1 Pro
38 tokens/sec
DeepSeek R1 via Azure Pro
28 tokens/sec
2000 character limit reached

A Unified Approach to Error Bounds for Structured Convex Optimization Problems (1512.03518v1)

Published 11 Dec 2015 in math.OC, cs.LG, math.NA, and stat.ML

Abstract: Error bounds, which refer to inequalities that bound the distance of vectors in a test set to a given set by a residual function, have proven to be extremely useful in analyzing the convergence rates of a host of iterative methods for solving optimization problems. In this paper, we present a new framework for establishing error bounds for a class of structured convex optimization problems, in which the objective function is the sum of a smooth convex function and a general closed proper convex function. Such a class encapsulates not only fairly general constrained minimization problems but also various regularized loss minimization formulations in machine learning, signal processing, and statistics. Using our framework, we show that a number of existing error bound results can be recovered in a unified and transparent manner. To further demonstrate the power of our framework, we apply it to a class of nuclear-norm regularized loss minimization problems and establish a new error bound for this class under a strict complementarity-type regularity condition. We then complement this result by constructing an example to show that the said error bound could fail to hold without the regularity condition. Consequently, we obtain a rather complete answer to a question raised by Tseng. We believe that our approach will find further applications in the study of error bounds for structured convex optimization problems.

Citations (174)

Summary

  • The paper introduces a unified framework for analyzing error bounds in structured convex optimization by relating them to concepts from set-valued analysis.
  • This approach effectively integrates existing results and applies to various problems, including nuclear-norm regularized loss minimization under specific conditions.
  • The framework provides a systematic methodology for analyzing convex problems and can potentially enhance convergence analyses of optimization methods in diverse applications.

Overview of Error Bounds in Structured Convex Optimization

The paper "A Unified Approach to Error Bounds for Structured Convex Optimization Problems" by Zirui Zhou and Anthony Man-Cho So presents an analytical framework for exploring error bounds in convex optimization. Error bounds serve as a pivotal tool to analyze the convergence rates of iterative methods used in optimization. The authors present a novel approach that integrates existing error bound results for convex optimization problems formed by the sum of a smooth convex function and a closed proper convex function. This provides a comprehensive method applicable to various scenarios including constrained minimization problems and regularized loss minimization formulations, which are prevalent in machine learning, signal processing, and statistics.

Strong Numerical Results and Claims

The paper's principal contribution is the introduction of a unified framework that effectively encapsulates existing error bound results in a transparent manner. This is achieved by elucidating the relationship between error bounds and set-valued analysis concepts such as calmness and metric sub-regularity. Specifically, the authors establish that examining the calmness of a set-valued mapping, derived from the problem's optimal solution set, is instrumental in verifying error bounds. The paper demonstrates this approach by proving that certain structured convex optimization problems possess the error bound property under specific conditions. For instance, the nuclear-norm regularized loss minimization problems show an error bound under a complementarity-type regularity condition.

Implications and Speculations

The proposed analytical framework has significant implications for both theoretical development and practical applications in the field of convex optimization. Theoretically, it provides a robust methodology to extend the paper of error bounds beyond traditional, ad hoc approaches, offering a systematic way to analyze various convex optimization problems. Practically, this means that researchers and practitioners can potentially leverage the framework to enhance the convergence analyses of first-order optimization methods, expediting problem-solving processes across multiple domains concerned with large scale and complex data.

Furthermore, this research opens avenues for future work, particularly in the exploration of error bounds in structured optimization problems where the regularizer is non-polyhedral. The insights afforded by this framework could lead to advancements in optimizing problem formulations synonymous with cutting-edge machine learning applications, thereby improving algorithmic efficiency and outcomes.

Conclusion

In conclusion, the paper contributes a significant shift in handling error bounds for structured convex optimization. Through the lens of set-valued analysis, it unifies disparate results into a coherent methodology that can be applied to a broad array of convex problems. Its application to non-polyhedral regularizers such as nuclear norms signifies an exciting frontier for expanding the framework's utility, encouraging further exploration in contemporary optimization challenges. This work underscores the intricate relationship between convex analysis and optimization convergence, setting a precedent for novel research trajectories in the field of AI and beyond.